Pro-Russian activists rallied in the eastern heart-land of Ukraine's ousted leader today, after Moscow threatened to cut off gas to its ex-Soviet neighbour following its tilt toward the West.

Rallies in industrial cities that rely on Russia for trade and whose cultural roots lie closer to Moscow than Kiev come, as Kremlin-backed troops tighten their grip on the flashpoint peninsula of Crimea.

The predominantly Russian-speaking southern and eastern swathes of Ukraine have been in upheaval, since three months of deadly protests brought new pro-European leaders to power in Kiev, whom they view with disdain and mistrust.